Structure of fluid container and method and apparatus for producing the fluid container

ABSTRACT

A fluid container for packing a product includes a check valve for each container member. A bonding structure of check-valves to a fluid container and a production method and apparatus of fluid container are disclosed in detail where the check valve is capable of reliably keeping the expansion of the fluid container without any fluid leakage after inflating the fluid container. As the check-valve is bonded to only one of thermoplastic container films, both films of the check-valve are fixed to one of the container films, thereby preventing the reverse flow by tightly closing the check valve. The manufacturing apparatus includes an up-down roller controller which precisely positions the films to form the check valve. The manufacturing apparatus can produce the fluid container with high reliability by having a belt conveyor specially designed for cooling down the heat sealed films before separating from the belt conveyor without damage.

FIELD OF THE INVENTION

This invention relates to a structure of a fluid container and amanufacturing apparatus for producing the fluid container, and moreparticularly, to a bonding structure of the check valve capable ofreliably keeping the expansion of the fluid container without any fluidleakage after inflating the fluid container and to the production methodand apparatus to produce the fluid container incorporating the bondingstructure of the check valves.

BACKGROUND OF THE INVENTION

A styroform packing material has been used for a long time for packingcommodity and industrial products. Although the styroform packagematerial has a merit such as a good thermal insulation performance, ithas also various disadvantages: recycling the styroform is not possible,soot is produced when it burns, a flake or chip comes off when it issnagged because of it's brittleness, an expensive mold is needed for itsproduction, and a relatively large warehouse is necessary to store it.

Therefore, to solve such problems above, other packing materials andmethods have been proposed. One method is a fluid container of sealinglycontaining a liquid or gas. The fluid container has excellentcharacteristics to solve the problems in the styroform. First, becausethe container is made of only thin sheets, it does not need a largewarehouse to store it unless the container is inflated. Secondly, a moldis not necessary for its production because of its simple structure.Thirdly, the fluid container does not produce a chip or dust which hasadverse effect on precision products. Also, recyclable materials can beused for the films of the fluid container. Further, the fluid containercan be produced with low cost.

FIG. 1A shows an example of fluid container in the conventionaltechnology. The fluid container 10 a is composed of first and secondthermoplastic films 13 and 14, respectively, and a check valve 11.Typically, each thermoplastic film is composed of three layers ofmaterials: polyethylene, nylon and polyethylene which are bondedtogether with appropriate adhesive. The first and second thermoplasticfilms are heat-sealed together around rectangular seal portions 12 a, 12b after the check valve is attached. Thus, one container bag 10 a sealedwith the heat seal portions 12 a, 12 b is formed such as shown in FIG.1A.

FIG. 1B shows an example of the manufacturing apparatus for the fluidcontainer, including first and second plastic film stocks 13 a and 14 arespectively, a first heat seal device 15 for attaching a check valve11, a sensor device 16 to control for supplying elongated plastic films13 c and 14 c, a second heat device 17 for right-left heat seal portions12 a, a third heat seal device 18 for upper-lower heat seal portions 12b, and film feed rollers 19.

Materials for the first and second plastic films are supplied aselongated plastic films 13 b and 14 b from the rolled film stocks 13 aand 14 a such as shown in FIG. 1B or FIG. 1C. The sensor device 16 isused to drive the feed rollers 19 and to control a feeding speed of theplastic films by, for example, by sensing marks printed on the elongatedplastic film 13 b or 14 b.

FIG. 1C shows an example of the first heat seal device 15, includingupper and lower heat seal elements 15 a and 15 b, a check valve supplier15 c, heater assemblies 15 d and check valves 11. The check valves 11are pre-installed on the check valve supplier 15 c. After the elongatedfilms 13 b, 14 b for one container package are supplied, the check valvesupplier 15 c supplies the check valve 11 between the first and secondelongated films 13 b and 14 b by rotating about its axis. The heaterassemblies 15 d are embedded in both the heat seal elements 15 a-15 band maintain the surfaces to contact the films 13 b and 14 b at anappropriate fusing temperature of the plastic film. By sandwiching thecheck valve 11 between the upper and lower heat seal elements 15 a and15 b, the check valve 11 is fused together with both the first and thesecond plastic film 13 b, 14 b and attached at a predetermined positionof the fluid container.

Referring back to FIG. 1B, after installation of the check valve 11 atthe stage of the first heat seal device 15, the elongated plastic films13 b, 14 b are fused together to form the right-left heat seal portions12 a of the fluid container at the stage of the second heat seal device17. Finally, the films 13 b, 14 b are fused together to form theupper-lower portions 12 b at the stage of the third heat seal device 18,and the fluid container with one check valve shown in FIG. 1 isproduced.

FIGS. 2A-2B show an example of a fluid container 10 b with multiplecontainer members where each container member is provided with a checkvalve. A main purpose of having multiple container members is toincrease the reliability. Namely, even if one of the container memberscauses an air leakage for some reason, the fluid container can stillfunction as a cushion of package because other container members areintact. Thus, in order to achieve this purpose, each container memberhas an independent room which is inflated independently.

With reference to FIG. 2A, this fluid container 10 b is made of thefirst and second thermoplastic films which are bonded together around arectangular periphery 23 a and further bonded together at each boundaryof two container members 22 so that a guide passage 21 and containermembers 22 are created. When the first and second thermoplasticcontainer films are bonded together, as shown in FIG. 2A, the checkvalves 11 are also attached to each inlet port of the container member22. By attaching the check valves 11, each container member 22 becomesindependent from the other. The inlet port 24 of the fluid container 10b is used when filling a fluid (typically an air) to each containermember 22 by using, for example, an air compressor.

FIG. 2B shows an example of the fluid container 10 b with multiple checkvalves when it is filled with the fluid. First, each container member 22is filled with the fluid from the inlet port 24 through the guidepassage 21 and the check valve 11. To avoid a rupture of the containermembers by variations in the environmental temperature, the fluid intothe container is typically stopped when the container member 22 isinflated at about 90% of its full expansion rate. After filling thefluid, the expansion of each container member is maintained because eachcheck-valve 11 prevents the reverse flow. Typically, the air compressorhas a gage to monitor the supplied air pressure, and automatically stopssupplying the air to the fluid container 10 b when the pressure reachesa predetermined value.

The check valve 11 is typically made of two rectangular thermoplasticvalve films which are bonded together to form a fluid pipe. The fluidpipe has a tip opening and a valve body to allow a fluid flowing throughthe fluid pipe from the tip opening but the valve body prevents thereverse flow. More details of the check-valve example are described inthe U.S. Pat. Nos. 5,209,264, 4,708,167 and 5,927,336. This type ofcheck valve is produced before manufacturing the fluid container andattached to it such as shown in FIG. 1C. Therefore, this type of checkvalve is often called an out-line valve. On the other hand, a valvewhich is produced in the process of making a fluid container, is calledan in-line valve. Preferably, the present invention is applied to thein-line valve, although the present invention is also applicable to theout-line check.

Fluid containers are becoming more and more popular. However, there areproblems to solve, for example, when the fluid container 10 b isinflated, both sides 23 a and 23 b of the check valve body is pressedinwardly by the expansion of the container member 22. The directions ofthe pressing force is shown by arrows 25 in FIG. 2C. As a result, thecheck valves 11 become wavy such as shown in FIG. 2D although the bondedportion was straight before the fluid container 10 b is inflated.

As mentioned above, the check valve 11 is typically made of twothermoplastic films. It should be noted that sometimes by the pressurenoted above, a gap is created between the thermoplastic films 11 a andthe check-valve 11 of the container member 22. Thus, the fluid is leakedthrough the gap as shown in FIG. 2E. The leakage of the check valve 11 ais shown by an arrow 27. In other words, the reverse flow in thecontainer member corresponding to the check valve 11 a occurs and thefluid from the container member 22 flows into the guide passage 21 inthis example. This is a serious problem of the fluid containers in theconventional technology. As long as there is no gap between the twothermoplastic films, the reverse flow is prevented as shown in the wavycheck valves 11 b and 11 c of FIG. 2E.

There is another problem which is involved in the production of thefluid containers. This problem is related to the installation of thecheck valves: it is not easy to accurately attach the check valve toeach container member of the fluid container film. Therefore, theinaccurate installation of the check valve also sometimes causes aleakage problem.

As described in the foregoing, the fluid container using the checkvalves is highly useful for packing commodity products and industrialproducts instead of the styroform packing. However, since there areleakage and other problems in the fluid containers as described above,it is necessary to improve the performance of check valves in the fluidcontainer and the production efficiency for producing the fluidcontainers to reduce the overall cost.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide astructure of fluid container and a method and apparatus for producingthe fluid containers with high efficiency and high reliability.

It is another objected of the present invention to provide a bondingstructure of an in-line check-valve formed in fluid members of a fluidcontainer, which is capable of reliably keeping the expansion of thefluid container without any fluid leakage after inflating the fluidcontainer.

It is a further object of the present invention to provide a method andapparatus for producing the fluid container having the above bondingstructure of the check-valve.

More specifically, one aspect of the present invention is a structure ofthe fluid container for sealingly containing a fluid and having a checkvalve of unique structure. The fluid container fluid container iscomprised of first and second container films superposed with each otherwhere predetermined portions of the first and second thermoplasticcontainer films are bonded, thereby creating a plurality of containermembers, and a check valve established at an input of each containermember between the first and second container films for allowing a fluidflow of only one predetermined direction, said check valve being formedof first and second check valve films juxtaposed with each other.

The check valve is bonded to one of the first or second container filmfor tightly closing the check valve when a reverse flow of the fluid isabout to occur, thereby preventing the reverse flow. Accordingly, bothtwo films of the check valve are curved in the same manner as one of thecontainer film to which the check valve is bonded when the fluidcontainer is inflated. Thus, the two bonded films of the check valve aretightly sealed and the expansion of the fluid container is reliablymaintained after the fluid container is inflated.

Another aspect of the present invention is a method for producing thefluid container having the above noted structure. The method includesthe steps of superposing first and second check valve films on a firstcontainer film, bonding the first and second check valve films to thefirst container film for creating a plurality of check valves,superposing a second container film on the first container film whilesandwiching the check valves therebetween, and bonding the firstcontainer film, the first and second check valve films and the secondcontainer film, thereby creating a plurality of container members wherethe check valve is positioned at each input of the container member.

A further aspect of the present invention is an apparatus for producingthe fluid container having the above noted structure. The productionapparatus is comprised of means for feeding films which feeds a firstcontainer film, first and second check valve films and a secondcontainer film, wherein the first and second check valve films aresandwiched between the first and second container films, a feed sensorfor detecting a position of a mark printed on either the first or secondcheck valve film to feed the films, an up-down roller controller foradjusting positions of the first container film and the first and secondcheck valve films, means for bonding the first container film and thefirst and second check valve films, thereby creating check valves, andmeans for bonding the first container film, the first and secondcontainer films and the second container film, thereby creating aplurality of container members and inlet portions of the check valves.The up-down controller adjusts the position of the check valve films bydetecting the mark for determining the position of check valve.

According to the present invention, the structure of check valves to bebonded to the fluid container and the production apparatus for producingthe fluid containers enable the fluid container of reliably keeping theexpansion of the fluid container without any fluid leakage afterinflating the fluid container. The up-down roller controller in themanufacturing apparatus for producing the fluid containers can preciselyposition the films to firmly form the in-line check valve. Also, thebelt conveyer in the manufacturing apparatus helps to form the heat sealportions without creases. As a result, the manufacturing apparatus inthe present invention can produce the fluid containers of highreliability and low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram showing an example of a typical fluidcontainer in the conventional technology, and FIGS. 1B-1C are schematicdiagrams showing examples of apparatus for producing the fluidcontainers in the conventional technology.

FIGS. 2A-2E are schematic diagrams showing a structure of a fluidcontainer having multiple container members with use of check valves inthe conventional technology for explaining the problems involvedtherein.

FIG. 3 is a schematic diagram showing an example of a fluid containerhaving a bonding structure of check valves in the present invention.

FIGS. 4A-4B are schematic diagrams showing an example of a bondingstructure of the check-valve in the present invention in more detail.

FIG. 5 is a schematic diagram showing the cross sectional view of thecheck valve of the present invention for explaining how the two checkvalve films in pairs are tightly closed when the reverse flow happens.

FIGS. 6A-6B are schematic diagrams showing the cross sectional view ofthe check valve of the present invention when the fluid container isinflated.

FIG. 7A is a schematic diagram showing an apparatus for producing thefluid containers having the bonding structure of the check valve in thepresent invention, and FIGS. 7B and 7C are schematic diagrams showing arelationship between a mark on the check valve film and the scanningarea of the sensor.

FIGS. 8A-8C are schematic diagrams showing bonding processes to producethe fluid containers including the in-line check valves in the presentinvention.

FIGS. 9A-9B are schematic diagrams showing cross sectional view of otherembodiments of the check valve structure in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and apparatus for producing afluid container with a reliable structure of check valve. As mentionedin the background of the invention, the check valves for the fluidcontainer in the conventional technology are not reliable when thecontainer is inflated. As shown in FIG. 2D, the sealed portions of thecheck valve are pressed inwardly and the check valve body becomes wavy.As a result, the fluid pipe in the check valve to prevent the reverseflow is easily opened, thereby causing the leakage. Also, the checkvalve needs to be attached more accurately to the fluid container.

A check valve in the present invention is designed to solve theseproblems. To avoid the check valve wavy, the check valve is not bondedto both container plastic films, but to only one of the containerplastic films. Also, to increase the accuracy of attaching the checkvalve to the container members, a check valve having a special structureis used for the fluid container in the present invention. Here, itshould be noted that the term “fluid” includes gas and liquid, althoughsometimes may be referred to as an “air” for simplicity.

Now, the present invention is described in detail with reference to theaccompanying drawings. FIG. 3 shows an example of structure of a fluidcontainer 30 in the present invention. In this example, the width W ofthe fluid container 30 is constant. The fluid container 30 is made offour thermoplastic films; two container films 31 a-31 b and two checkvalve films 32 a-32 b. The two container films 31 a-31 b are used toform an overall fluid container, and the two check valve films 32 a-32 bare used to form in-line check valves 38 in the manufacturing process.

These films are supplied respectively by the rolled film stocks 31 a, 31b and 32 a-32 b such as shown in FIG. 7A. The four films are juxtaposed(laminated) in the order of the first container film 31 a, first valvefilm 32 b, second valve film 32 a and second container film 31 b asshown in FIG. 3. Then, through three stages of the manufacturingprocess, the four films 31 a, 31 b and 32 a-32 b are bonded (typicallyheat-sealed) together to make a plurality of container members 34, aguide passage 33, and check valves 38.

In this example, the fluid (ex., air) is introduced through the guidepassage 33 and supplied to each container member 34, through each checkvalve 38. As another optional embodiment of the present invention, thefluid can be directly supplied to each container member 34 through thecorresponding check valve 38 without the guide passage 33. It should benoted that the four elongated plastic films 31 a-31 b and 32 a-32 b arefed in a manufacturing flow direction indicated by an arrow H of FIG. 3.

The container members 34 are rectangularly partitioned by upper-lowerseal (bonded) portions 39 a and right-left seal portions 39 b. Thesecontainer members 34 are formed so that they are inflated in a directionvertical with the manufacturing flow direction H. Further, ordinarily,many container members 34 are formed which are aligned in the flowdirection H. Although, in this example, the shape of the containermember is rectangular, it is not limited to the rectangular and could beany shape which satisfies the customer's specific needs. Also, althoughthe fluid container having multiple container members are shown, itcould be composed of a single container member.

In this example, the check-valve inlet 33 a is open to the guide passage33, and the container member 34 is heat-sealed by the upper-lower andright-left seal portions 39 a and 39 b. Thus, each container member 34is independent from one another except for the guide passage 33. In thisconfiguration, the fluid can be supplied to inflate the containermembers 34 through the guide passage 33 and the check valve inlet 33 a.

FIGS. 4A and 4B show the structure of the check valve 38 of the presentinvention in more detail where FIG. 4A is a top view and FIG. 4B is across sectional view. FIG. 4B shows the cross sectional view of thecheck valve 38 taken along the line II in FIG. 4A. Further, the crosssectional view of FIG. 4B shows the case where the fluid is not suppliedto the container member 34.

In FIGS. 4A and 4B, reinforcing seal portions 42 are formed near thecheck valve inlet 33 a such as shown in FIG. 4A. These portions areplaced in a manner of contacting each edge of the inlet portion 33 asuch as shown in FIG. 4A. The seal portions 42 reinforce a boundarybetween the guide passage 33 and the container member 34, and preventthe container member 34 from a rupture when it is inflated. In thepresent invention, the reinforcing seal portions 42 is not essential andcan be omitted.

In the fluid container 30, the two check valve films 32 a and 32 b arejuxtaposed (superposed) and sandwiched between the two container films31 a and 31 b near the guide passage 33, and fixing seal portions 41-42,35 and 37. These fixing seal portions 41-42 are referred to as outletportions, the fixing seal portion 35 is referred to as an extended (orwidened) portion, and the fixing seal portion 37 is referred to as anarrow down portion. These fixing seal portions also form the structureof the check valve 38 and fix the valve to the first container plasticfilm 31 a at the same time. The fixing seal portions 35 are made byfusing the check valve plastic films 32 a and 32 b only with the firstplastic container film 31 a. As a result of this bonding, the checkvalve 38 is constructed inside the container member 34.

As has been described, the check valve 38 is made of the two flexiblethermoplastic films 31 a-31 b and a fluid pipe 48 is created between thefirst check valve film 32 b and the second check valve film 32 a. Howthe fluid passes through the check valve 38 is shown by white arrowsindicated by the numbers 47 a, 47 b and 47 c. The fluid is supplied fromthe guide passage 33 through the fluid pipe 38 to the container member34.

In the check valve 38, the regular fluid relatively easily flows throughthe fluid pipe 48 although there exist the fixing seal portions 35, 37and 41-42. However, the reverse flow in the valve will not easily passthrough the fluid pipe 48. In other words, if the reverse flow occurs inthe fluid pipe 48, it is prevented because of a pressure of the reverseflow itself. By this pressure, the two surfaces of check valve films 32a and 32 b which face each other, are brought into intimate contact suchas shown in FIG. 5 as will be explained later.

As has been described, in FIGS. 4A-4B, the fixing seal portions 35, 37and 41-42 also work for guiding the fluid to flow in the check valve 38.The fixing seal portions are comprised of the portions 41 a, 42 a, 35 aand 37 a which bond the two check-valve films 32 a and 32 b together,and the portions 41 b, 42 b, 35 b and 37 b which bond the firstcontainer film 31 a and the first check valve film 32 b together.Accordingly, the fluid pipe 48 in the check valve 38 is created as aspace formed between the two check valve films 32 a-32 b which excludesthe fixing seal portions 41 a, 42 a, 35 a and 37 a.

Further in FIG. 4A, the fixing seal portion 37 are composed of twosymmetric line segments (narrow down portions) extended in an upwarddirection of the drawing, and a width of the fluid pipe 48 is narroweddown by these portions 37. In other words, the regular flow can easilypass through the fluid pipe to the container member 34 when it passesthrough the wide space to the narrow space created by the narrow downportions 37. On the other hand, the narrow down potions 37 tend to stopthe reverse flow from the container member 34 when the fluid goes backthrough the narrow space created by the narrow down portions 37.

The extended portion 35 is formed next to the narrow down portions 37.The shape of the extended portion 35 is similar to a heart shape to makethe fluid flow divert. By passing the fluid through the extended portion35, the fluid diverts, and the fluid flows around the edge of theextended portion 35 (indicated by the arrow 47 b). When the fluid entersthe container member 34 (forward flow), the fluid flows naturally in theextended portion 35. On the other hand, the reverse flow cannot directlyflow through the narrow down portions 37 because the reverse flow hitsthe extended portion 35 and is diverted its direction. Thus, the reverseflow cannot practically occur because the flow is not natural.Therefore, the extended portion 35 also functions to prevent the reverseflow.

The outlet portions 41-42 are formed next to the extended portion 35. Inthis example, the outlet portion 41, extended in perpendicular to the(manufacturing) flow direction H, is formed at the upper center of thecheck valve 38, and the two outlet portions 42 to extended to the(manufacturing) flow direction H are placed symmetrically with respectto the outlet portion 41. There are several spaces among these outletportions 41 and 42. These spaces constitute a part of the fluid pipethrough which the fluid can pass as indicated by the arrows 47 c. Theoutlet portions 41-42 are formed as a final passing portion of the checkvalve 38 when the fluid is supplied to the container member 34 and thefluid diverts in four ways by passing through the outlet portions 41-42.

Accordingly, the reverse flow from the container member 34 cannot easilypass through the fluid pipe 48. Thus, the reverse flow is stopped insome degrees by the outlet portions. As has been described, the fluidpassing from the guide passage 33 to the container member 34 isrelatively smoothly propagated through the check valve 38. Further, thenarrow down portions 37, extended portions 35 and outlet portions 41-42formed in the check valve 38 work to prevent the reverse flow.

FIG. 5 is a cross sectional view showing an effect of the check valve 38of the present invention. This example shows an inner condition of thecheck valve 38 when the reverse flow tries to occur in the containermember 34. First, the fluid hardly enters in the fluid pipe 48 becausethe outlet portions 41 and 42 work for the fluid such that the reverseflow will not easily enter in the outlet portions. Instead, the fluidflows in a space between the second container film 31 b and the secondvalve film 32 a such as indicated by the arrows 51, and the space isinflated such as shown in FIG. 5. By this expansion, the second checkvalve film 32 a is pressed to right, and at the same time, the firstvalve film 32 b is pressed to left. As a result, the two check valvefilms 32 a and 32 b are brought into tight contact as indicated with thearrows 52. Thus, the reverse flow is completely prevented.

FIGS. 6A-6B are simplified cross sectional drawings of the check valve38 viewed from the guide passage of the fluid container 30. FIG. 6Ashows the condition that the container members are inflated until abouta half of the full inflation. FIG. 6B shows the condition that thecontainer members 34 are inflated fully by the fluid. The first andsecond container films 31 a and 31 b are inflated such as shown in FIGS.6A-6B, and the check valve 38 is shown by the cross hatching on thefirst container film 31 a.

Each container member 34 is chained by the right-left seal portions 39b. Because the narrow down portions 37, extended portion 35 and outletportions 41-41 in FIGS. 4B-4C are placed closely, their bonding forcewith the first container film 31 a is strong enough to keep fixing thecheck valve 38 to the film 31 a even if the container member 34 is fullyinflated. Therefore, the check valves 38 bonded only to the firstcontainer film 31 a are curved along the surface deflection of thecontainer film 31 a.

In other words, both the two check-valve films forming the check valve38 are curved in the same direction as that of the first container film31 a (the fluid pipe in the check-valve keeps to be closed) whiletightly contacting with one another. Thus, FIGS. 6A-6B clearly show thatthe design of the check valves bonded only to one of the container filmscan effectively prevent the check valve 38 from leaking when thecontainer member 34 is inflated. As shown in FIG. 5, since the checkvalve 38 is tightly closed when the reverse flow about to occur, thereverse flow of the fluid is effectively prevented by the structure ofthe check valve in the present invention.

Next, the manufacturing process and apparatus for producing the fluidcontainer are described with reference to FIGS. 7A-7C and 8A-8C. FIG. 7Ashows an example of a preferred embodiment of a manufacturing apparatusfor the fluid container in the present invention. As has been described,the check valves are constructed during the manufacturing process of thefluid containers.

The manufacturing apparatus 70 is comprised of a film feeding means 71,film conveying rollers 72, a valve heat seal device 73, an up-downroller controller 74, a sensor for feeding elongated plastic films 79, aright-left heat seal (bonding) device 75, a belt conveyer for right-leftheat seal 77, and an upper-lower heat seal (bonding) device 76.

The up-down roller controller 74 is provided to the manufacturingapparatus 70 in order to improve a positioning performance of the checkvalves. The up-down controller 74 moves the rollers 74 b inperpendicular (upward or downward) to the manufacturing flow direction Hin order to precisely adjust a position of the check valve. Also, thebelt conveyer 77 is provided to the manufacturing apparatus 70 in orderto improve a heat seal performance for forming right-left heat sealportions 39 b shown in FIG. 3.

With reference to FIG. 7A, an overall manufacturing process isdescribed. First, the film feeding means 71 supplies elongated checkvalve films 32 a and 32 b which are juxtaposed (superposed) with eachother, and the container films 31 a and 31 b to the following stages ofthe manufacturing process. The film conveying rollers 72 at variouspositions in the manufacturing apparatus 70 guide and send each filmforward.

Every time each elongated film is advanced by a length equal to onefluid container in the manufacturing flow direction, heat seal processesare performed at the three stages of the process. The first stage ofheat sealing process is done by using the valve heat seal device 73.This is the process for forming the structure of in-line valve 38. Theposition of the valve 38 is precisely adjusted by the up-down rollercontroller 74. The detailed method will be explained later withreference to FIGS. 7B-7C.

The second stage of the heat sealing process is done by using theright-left heat seal device 75 and the belt conveyer 77 for right-leftheat seal. The belt conveyer 77 is used for prevent the right-left heatseal portion from extending. The belt conveyer 77 has two wheels 77 band a flexible rubber 77 a which sticks to the film 31 b and moves atthe same feed speed of the films. Therefore, the belt conveyer 77 keepsthe films as is until the seal portion passes the conveyer 77. Also, theheat seal portions with a high temperature are naturally cured whilethey are stuck to the rubber 77 a. As a result, the belt conveyer 77prevents the right-left seal portions 39 b extended or crinkled.

The third stage of the sealing process is performed by the upper-lowerheat seal device 76. This is the final heat seal process to produce thefluid container 30. The fluid containers which are produced in the formof one long sheet may be rolled again, or may be cut and heat-sealedagain to make a sack-like form for a cushion of package. Processes ofinflating the produced fluid container and packaging the products withthe fluid container may be added.

The control processes for supplying the films in the manufacturingmachine 70 are discussed with reference to FIGS. 7A-7C. Feeding of theelongated films 31 a-31 b, 32 a and 32 b is controlled by using thesensor 79 and the film conveying rollers 72. The sensor 79 is comprisedof, for example, a light emitting diode (LED) 79 a and a photo-receiver79 b for sending the light from the LED. The sensor 79 detects an edgebetween the transparent part 80 b and a mark 78 which is printed inadvance on one of the check valve films 32 a and 32 b such as shown inFIG. 7B. The sensor 79 causes to drive the film conveying rollers 72such that each of the elongated plastic films 31 a, 31 b, 32 a and 32 bin the size of one fluid container is supplied. Thus, the manufacturingapparatus 70 includes a main controller for controlling the overallfeeding process of the elongated films 31 a, 31 b, 32 a and 32 b basedon the signals from the sensor 79.

The manufacturing apparatus 70 also includes a precise control means forprecisely positioning the check valves to a position of the printed mark78 (in FIG. 7B) by using the up-down roller controller 74 such as shownin FIGS. 7A. The up-down controller 74 is configured by a sensor 74 aand an up-down roller 74 b. The films are typically transparent and themarks 78 are printed with an appropriate color such as white. The sensor74 a is comprised of, for example, a light emitting diode (LED) 74 a(1)and a photo-receiver 74 a(2) for detecting the light from the LED.

The LED 74 a(1) emits a light which passes through the films 31 a and 32a-32 b as indicated by the arrow in FIG. 7A. If the light passes throughthe transparent part 80 a of the film 32 a, then an energy of the lightreceived by the photo-receiver 74 a(2) will be large. Also, if the lightpasses through the white mark 78, the detected light will be smallbecause the light cannot easily pass through the white paint. Therefore,the sensor 74 a can differentiates the transparent part 80 b from thewhite mark 78.

By using this information, the manufacturing apparatus 70 controls theposition of the valve films 32 by driving the up-down rollers 74 b inperpendicular (upward or downward) to the manufacturing flow direction Hsuch that the light of the LED passes through the edge 80 after thefilms are supplied in the manufacturing flow direction H such as shownin FIG. 7C. In other words, the films always have some tension in theflow direction H. Therefore, if the up-down controller moves the up-downrollers 74 b upward, then the films are fed forward. In contrast, if thecontroller moves them downward, then the films are fed backward. In thismanner, the position of the films are controlled. In FIG. 7C, theshadowed area 80 a shows an area scanned by the sensor 74 a while theelongated films 32 a are sent in the direction H.

With reference to FIGS. 7A and 8A-8C, the three stages of the heat sealprocess is described in detail. In general, the heat seal device in eachstage 73, 75 and 76 includes heaters and a stamping die which forms theheat seal portions required in the stage. Each die is heated andmaintained at a predetermined temperature to appropriately fuse and bondthe films together.

The first container film 31 a and the check valve films 32 a and 32 bare superposed and heat-sealed by the valve heat seal devices 73, asshown in FIG. 8A. The heat seal device includes the heaters and thestamping die, which forms the fixing seal portions 81. As has beendescribed, the color marks 78 are used to control the position of thecontainer films 31 a and the check valve films 32 a-32 b such that thefixing portions are formed in the center of the color mark 78. Byforming the fixing seal portions 81, the check-valve 38 can be createdwhich is fixed to the first container film such as shown in FIG. 6B.

On the second stage of the heat sealing process (at the upper right-leftheat seal device 75 and lower belt conveyer 77), the right-left heatseal portions 39 b are formed by additionally superposing the containerfilm 31 b and heat-sealing the films 31 a-31 b and 32 a-32 b. The upperright-left heat seal device 75 includes the heaters and the stampingdie, which forms the shape of the right-left heat seal portions 39 b.The fixing portion 42 of the check valve is heat-sealed as needed inthis process. As has been described, this heat seal process uses thebelt conveyer 77 in FIG. 7A which is provided to form the right-leftportions 39 b without creases or wrinkles.

On the third stage of the heat sealing process (at the upper-lower heatseal device 76), the upper-lower heat seal portions 39 a (indicated bythe shadow area in FIG. 8C) are formed by heat-sealing the films 31 a-31b and 32 a-32 b. The upper-lower heat seal device 76 includes theheaters and the stamping die, which forms the shape of the upper-lowerheat seal portions 39 b. Through the above three stages of the heatsealing process, the fluid container members 34, the inlet portions 33a, the guide passage 33 and the fixed seal portions (in-line valve) 81are created, and the production of the fluid containers is completed.

As shown in FIG. 8C, the inlet portion 33 a are covered by the mark 78.Therefore, if heat resist paint is optionally used for printing the mark78, the inlet portion 33 a of the valve 38 will not be bonded togethereven if the inlet portion 33 a tries to be heat-sealed with otherportions. In this case, the cavity of the inlet portion 33 a in thestamping die to create the inlet portion is not necessary. Thus, thedesign of the stamping die becomes simpler if the heat resist paint isused.

The present invention is not limited to the embodiments mentioned above.For example, in the above example, the two check valve films 32 a and 32b are used. However, instead of using the two valve films, one checkvalve film may be used for the same structure by folding it in two.Also, more than two check valve films may be used for the similarpurpose. For example, as shown in FIG. 9A, an additional check valve 32c is placed between check valve films in pairs 32 a and 32 b. Theadditional check valve film 32 c is bonded to one of the check valvefilms (in this example, film 32 b) and can be brought into tight contactor opened to another check valve (in this example, film 32 a) in orderto prevent the reverse flow in the fluid pipe.

Further, the shape of the check valve film 32 c is not limited to aparticular shape to work for only one check valve sheet such as shown inFIG. 9A. It may be a “V” shape to operate as a check valve for bothdirections such as shown in FIG. 9B. Further, as other embodiments ofthe present invention, such a configuration in which a plurality of thecheck valve films 32 c are placed between the check valves 32 a and 32 bis also possible.

As has been in the foregoing, the structure of check valves to be bondedto the fluid container and the production apparatus for producing thefluid containers enable the fluid container of reliably keeping theexpansion of the fluid container without any fluid leakage afterinflating the fluid container. The up-down roller controller in themanufacturing apparatus for producing the fluid containers can preciselyposition the films to firmly form the in-line check valve. Also, thebelt conveyer in the manufacturing apparatus helps to form the heat sealportions without creases. As a result, the manufacturing apparatus inthe present invention can produce the fluid containers of highreliability and low cost.

Although the invention is described herein with reference to thepreferred embodiments, one skilled in the art will readily appreciatethat various modifications and variations may be made without departingfrom the spirit and the scope of the present invention. Suchmodifications and variations are considered to be within the purview andscope of the appended claims and their equivalents.

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 7. A method of producing a fluid container for packing aproduct by sealingly containing a fluid therein, comprising thefollowing steps of: superposing first and second check valve films on afirst container film; bonding the first and second check valve films tothe first container film for creating a plurality of check valves;superposing a second container film on the first container film whilesandwiching the check valves therebetween; and bonding the firstcontainer film, the first and second check valve films and the secondcontainer film, thereby creating a plurality of container members wherethe check valve is positioned at each input of the container member. 8.A method of producing a fluid container as defined in claim 7, whereinsaid step of creating the check valves includes a step of positioningthe first and second check valve films by detecting positions of marksprinted on the first or second check valve film.
 9. A method ofproducing a fluid container as defined in claim 7, wherein the checkvalve includes: an inlet portion which introduces the fluid into thecheck valve; a pair of narrow down portions creating a narrow downpassage connected to the inlet portion; an extended portion whichdiverts the fluid coming through the narrow down passage; and aplurality of outlet portions which introduce the fluid from the extendedportion to the container member.
 10. A method of producing a fluidcontainer as defined in claim 7, wherein said step of bonding the firstcontainer film, the first and second check valve films and the secondcontainer film, includes the steps of: forming right-left bondingportions, thereby creating a part of the container members; and formingupper-lower bonding portions, thereby creating the rest of the containermembers and inlet portions of the check valves.
 11. A method ofproducing a fluid container as defined in claim 8, wherein said marksare color marks printed in advance on either the first check valve filmor the second check valve film.
 12. A method of producing a fluidcontainer as defined in claim 8, wherein said marks are printed with useof heat-resist paint.
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